Curable organopolysiloxane compositions and curable epoxy resin compositions are used as protective, coating, and sealing agents for semiconductor elements of such semiconductor devices as photocouplers, light-emitting diodes, solid-state imaging devices, etc. It is required that such curable organopolysiloxane compositions and curable epoxy resin compositions neither absorb nor scatter the light emitted or received from a semiconductor element. Furthermore, a cured object produced from these compositions should possess high strength and resistance to scratching.
A cured object obtained from a known curable organopolysiloxane composition comprising an organopolysiloxane with at least two silicon-bonded alkenyl groups per molecule, an organopolysiloxane with at least two silicon-bonded hydrogen atoms, and a hydrosilylation catalyst is characterized by low mechanical strength and low resistance to scratching. As far as the is concerned, with the lapse of time, an object obtained by curing the curable epoxy resin composition changes its color and becomes less permeable to light. This leads to decrease in reliability of semiconductor devices produced with the use of such a composition.
It is an object of this invention to provide a curable organopolysiloxane composition suitable for forming a cured object characterized by a high coefficient of refraction, excellent light permeability, high mechanical strength and resistance to scratching. It is a further object to provide a highly reliable semiconductor device covered with the aforementioned cured object.